Lighting unit



16 1,6 2 June 1927' c. A. B. HALvolsoN, JR. 3

LIGHTINEUNIT lnventr Cromwell AB. Holvorson, J1".

His Attorne Patented June 7, 1927 I UNITED STATES 1,631,632 PATENT OFFICE.

GBOMWEIIII A. B. HALVOBSON, J 1%., OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, CORRORATION OF NEW YORK.

LIGHTING UNIT.

Application filed February 28', 1925. Serial No. 12,425.

My invention relates to lighting units. More particularly the invention relates to lighting units which are especially adapted for highway lighting or for flood lighting.

5 Ordinarily highway lighting units are not used for flood lighting purposes but it is one of the objects of my invention, however, to provide means whereby such units may serve for flood lighting purposes. In the unit of my invention I contemplate the use of two sources of light: one a high power source for use during the early hours of the evening and for supplying light to a flood lighting reflector; the other a low power light source for use during the late hours of the night. The unit of this construction has a general light distribution and a special reflector located between the light sources which serves to concentrate light 2 upon one particular area for flood lighting purposes. I

The details of the unit are hereinafter more fully set forth and claimed, referencebeing had to accompanying drawing, in

which the figure shows the lighting unit of my invention in elevation and partly in section. 7

Referring more in detail to the drawing it will be seen that the; unit comprises an enclosing globe 2 in which the light sources 3 and 4 are located. These light sources are connected in any suitable manner with the source of current for producing the necessary light with suitable switches whereby the llghts may be turned on and off, either one at a time or simultaneously. For example, in the early hours of the evening it may be desirable to turn on the upper light source alone or both the light sources at 40 the same time and after a given hour, midnight for example, the upper light may be turned off, the lower alone serving as the source of light for the remainder of the night. In the preferred form of -construction I provide a main reflector 5 above the light source 4, which reflector may preferably' be in the form of an ellipsoidal reflector. In this combination the center of the light sourcewill be located at the focal 59 point F of the ellipsoid nearest the re- 'flector, while the second focal point F may be arranged to. fall at a point between the two light sources as indicated in the drawing. In the preferred form of construction 5 I contemplate the use of aparaboloidal reflector 6, the focal point of which coincides upper end of which the socket for the light source 4 is attached. The globe 2 as shown rests on a base element 8, which in turn is secured to the upper end of a stand or post 9. WVithin the base 8' there is provided a framework 10, to which the socket for the light sources 3 may be attached. Rest-ing on the upper part of the globe there is a suitable hood 11, which may be secured to the globe by means of series of screws 12.

It will be seen therefore that with a construction such as described and illustrated a highway lighting unit of attractive design and having a general light distribution may be used to secure also and at the same time a flood lighting beam without much additional expense, without detracting from the appearance and without at the same time producing objectionable shadows which might destroy the-artistic effect of the unit.

In the figure the axis 02-2: of the paraboloidal reflector 6 isshown inclined to the axis of the main reflector 5. With such a reflector tlierays that pass through the focal point F will be projected by the reflect-or 6 to the right parallel to the axis :vw while the other rays that strike the reflector 6 will be projected in different directions. The result therefore is an asymmetric distribution. When a plane glass reflector is used the reflected rays of the diverging beam will not be paralled as is the case when a parabo- -loidal reflector 6 isused but there will be What I claim as new and desire to secure by Letters Patent of the United States,.,is:--

In a lighting unit, an ellipsoidal reflector and a pair of light'sources located along the axis of the reflector, an auxiliary concave reflector located across said axis, one of said 5 light sources being located at one of the focal regions of the ellipsoidal reflector, said auxiliary reflector having a focal region coincident with another focal region of the ellipsoidal reflector, said ellipsoidalreflector serving to produce a beam along 10.

the axis of the unit and the auxiliary reflector serving to produce a beam diverging from the axis of the unit.

- In Witness whereof, I have hereunto set my hand this 26th day of February, 1925.

CROMWELL A. B. HALVORSON, Jr. 

